Transformers are widely used in modern radio frequency (RF) transceiver design to control signal flow. There are many conventional ways to implement the transformer using metal conductors routed in an integrated circuit. For example, an on-chip transformer can be implemented using a one-side coplanar design, a two-side coplanar design, a broadside design, or a hybrid design. The impedance transformation is critical in RF transceiver design to improve power efficiency.
How to achieve the on-chip transformer having better coupling efficiency and less coupling loss is highly desired.